622 EXPERIMENT STATION RECORD. 



varying amounts of oxygen (air), nitrate, caustic lime, and sulphuric 

 acid is discussed. 



It was found that horse manure as a rule contains denitrifying 

 organisms and these are usually of two kinds, one of them being also 

 found in straw. The organism found only in the manure reduces 

 nitrates in symbiosis with Bacterium coli and is identical with Bacillus 

 denitrificans I of Burri and Stutzer. The organism found both in the 

 manure and in straw is considered a variety of the Bacillus denitrifi- 

 ed us II isolated from straw by Burri and Stutzer. 



Denitrifying organisms are not present as a rule in cattle manure. 

 Those obtained from this source were identical with Bacillus denitrifi- 

 cans I of Burri and Stutzer. 



The reduction of nitrates due to the action of these organisms is 

 considerable, but decreases with the amount of organic matter in the 

 culture medium. Bacillus denitrificans I (in symbiosis with Bacterium 

 coli) completely reduced the nitrate in nutrient bouillon containing as 

 much as 0.7 per cent of that substance. Bacillus denitrificans II did the 

 same in bouillon containing as high as 0.8 per cent of nitrate. 



The exclusion of air as well as its free admission checked the deni- 

 trifying action of Bacillus denitrificans I, but were without effect upon 

 the action of Bacillus denitrificans II. 



Sulphuric acid is extremely active in preventing denitrification,0.17 

 per cent in the culture medium being sufficient to prevent the develop- 

 ment of the denitrifying organisms. 



Denitrifying organisms are less frequently present in cultivated soils 

 than in manure and are usually of a different kind. The denitrifying 

 organisms isolated from soils were Bacillus pyocyaneus, B. fiuorescens 

 liquefaeiens,a,\idB. denitrificanslll,im organism notpreviously described. 

 These organisms reduce nitrates as actively as those present in manure. 

 As in the case of the latter, the presence of sulphuric acid to the extent 

 of 0.17 per cent completely checked the activity of the soil organisms. 



Comparison of different phosphates, W. P. Brooks (Massachu- 

 setts Hatch itta. Rpt. 1897, pp. 16-19). — This is an account of experi- 

 ments during 1807 on 13 eighth-acre plats planted to corn. The 

 whole area had received an application of 600 lbs. of ground bone and 

 200 lbs. of muriate of potash per acre in 1800, before the laying out 

 of the plats. In 1897 each of the plats received a basal fertilizer of 

 potash-magnesia sulphate 50 lbs., nitrate of soda 30£ lbs., and sul- 

 phate of potash 12A lbs. per plat. In addition to this basal fertilizer 

 the different plats received phosphoric acid in the form of hoof meal, 

 bone meal, dissolved boneblack, acid phosphate, Navassa phosphate, 

 South Carolina rock phosphate, Florida soft phosphate, apatite, and 

 basic slag. 



" [The results show] that the yield on the plats to which phosphates were applied 

 varied without apparent relation to the availability of the phosphoric acid in the 

 materials nsed. . . . The unfavorable influence of the season aud possible differences 

 in natural fertility of the soil serve to obscure the action of the phosphates employed." 



